80.牙齦在健康情況下，以大於0.5 N來探測植體牙齦溝的深度（implant gingival sulcus），通常牙周探測具前端 （直徑0.5 mm）會落在下列何項解剖位置內？
(A)在植體牙齦溝內
(B)連接上皮
(C)結締組織內，靠近連接上皮端
(D)結締組織內，靠近齒槽骨端

Ericsson and Lindhe (1993) used the model of Berglundh et  al. (1991) referred to earlier and, hence, had both teeth and implants available for examination. The gingiva at mandibular premolars and the mucosa at correspondingly positioned implants (Brånemark System®) were, after extended periods of plaque control, considered clinically healthy. A probe with a tip diameter of 0.5 mm was inserted into the buccal “pocket” using a standardized force of 0.5 N. The probe was anchored to the tooth or to the implant and biopsies from the various sites were performed. The histologic examination of the biopsy material revealed that probing the dentogingival interface had resulted in a slight compression of the gingival tissue. The tip of the probe was located coronal to the apical cells of the junctional epithelium. At the implant sites, probing caused both compression and a lateral dislocation of the peri‐implant mucosa, and the average “histologic” probing depth was markedly deeper than at the tooth site: 2.0 mm versus 0.7 mm. The tip of the probe was consistently positioned deep in the connective tissue–abutment interface and apical of the barrier epithelium. The distance between the probe tip and the bone crest at the tooth sites was about 1.2 mm. The corresponding distance at the implant site was 0.2 mm.